CNN  — 

Hate crimes in the United States have increased to a point not seen in recent history, according to a new statistical report released Monday by the Federal Bureau of Investigation.

Thousands of hate crimes – 6,121 – were reported to the FBI in 2016, the report found. That’s up from 5,850 reported hate crime incidents in 2015. The figures are based on over 1,500 incident reports from law enforcement agencies around the country. Other than the increase in 2016, the number of hate crimes found each year by the FBI has decreased since the agency started collecting data in 1992. There were 8,759 hate crimes reported by the FBI in 1996, for instance, although more police departments took part in that survey.

The rise in 2016 reported by the FBI comes after observers have pointed to an increase in hate crimes and conversations about racial animus and hate speech have been central to political conversations nationwide.

The FBI’s report puts more statistical weight behind the argument that the 2016 election coincided with an increase in hate crimes, including by those purporting to be supporters of President Donald Trump.

In the days after the November 2016 election, an increase in racist slogans and hateful messages was reported, especially in schools. The Southern Poverty Law Center found 867 cases of hateful harassment or intimidation in the 10 days after the Nov. 8 election.

After coming under criticism for not speaking out, Trump responded by saying he was “so saddened” to hear about vitriol hurled by some of his supporters against minorities. “If it helps, I will say this, and I will say right to the cameras: Stop it,” Trump told CBS’ “60 Minutes” last year shortly after Election Day.

Trump was criticized again this summer as slow to respond to a violent gathering by white nationalists and neo-Nazis in Charlottesville, Virginia.

Researchers and advocates studying civil rights and hate crimes say the findings are just a small window into a much bigger problem. “Those figures from the FBI don’t represent the universe of hate crimes,” said Sim Singh, national advocacy manager for the Sikh Coalition. “It’s more likely it represents the tip of the iceberg.”

Shortcomings in the data are inevitable given that the FBI relies on voluntary participation by law enforcement, says Singh. This year, only about 11% of law enforcement agencies participating in the program submitted hate crime data for the report. The FBI publishes its hate crime statistics based on the Uniform Crime Reporting (UCR) Program. The UCR is routinely criticized for undercounting crimes.

But Ken Schwencke, a reporter for ProPublica who is investigating gaps in hate crime data, says the incomplete data the FBI provides is useful for getting an understanding of trends.

“One thing you can see in the data is these big swings during real life events,” he said. “After 9/11, there was a surge in reports of anti-Muslim violence.” What’s lost, he says, is any kind of detail about the magnitude of the problem or where it is problematic.

Schwencke explained some of the reasons the report is inadequate. Many victims do not report the crimes and even if they do, police departments often apply different criteria for tracking and reporting the crimes internally and to the FBI. In some cases, the largest departments in the country have failed to report cases that his organization has validated as hate crimes.

That’s made the FBI report an incomplete and piecemeal study of the phenomenon, he said. ProPublica is working with hundreds of local news organizations to verify reports of hate crimes in order to create a national database.

The Bureau of Justice Statistics, an agency within the Department of Justice, conducts surveys that shed some light on how many hate crimes happen. The agency found an average of 250,000 hate crime victimizations per year from 2004 to 2015. The Bureau of Justice Statistics compiled its numbers from the National Crime Victimization Survey, a large survey of households in the US.

Past research by the Anti-Defamation League found that at least 85 police agencies in cities with populations over 100,000 did not participate in the FBI’s annual report on hate crimes. For context, a 2010 Census report found that 285 cities have populations of at least 100,000.

For a broader look at hate crimes in the US, see CNN’s report with seven charts that explain hate groups.